Beach grooming refers to the practice of removing debris and seaweeds from sandy beaches. Grooming may be done by a variety of methods, but typically involves the use of large tractors with rakes that are pulled behind. Beach grooming is a widespread practice throughout the United States. In Southern California, for example, it is estimated that over 45% of the sandy coastline is groomed regularly.
There are several potential benefits associated with beach grooming. First, grooming may remove trash such as plastics and fishing gear which can be detrimental to wildlife. Second, beach grooming may improve aesthetics for beachgoers and shoreline property owners. In particular, the removal of seaweeds may reduce unpleasant smells and various "pests" associated with these macrophytes.
Nevertheless, recent studies have indicated that beach grooming may also be ecologically damaging. When seaweeds and seagrasses (known as 'wrack') are removed from the beach, an important component of the food chain is lost. Numerous species of crabs, crustaceans, and shorebirds all depend on these deposited 'macrophytes' for their food supply. Accordingly, regular grooming tends to reduce the biodiversity and biomass found on sandy beaches.
Additionally, beach grooming can remove significant quantities of sand and alter grain size. Because seaweeds help prevent the loss of finer sediments to the wind, groomed beaches tend to have a slightly coarser texture. Beach grooming can also repress natural features such as coastal dunes and the perennial grasses associated with them.
Finally, beach grooming can potentially impede the reproductive activities of animals which use the beach for breeding purposes. Sea turtles, as well as a number of seabirds and forage fish, lay their eggs on sandy beaches. If grooming activities coincide with the breeding seasons of these animals, eggs may be destroyed or damaged.
Dr. Jenifer Dugan of University of California, Santa Barbara has studied the effects of beach grooming on sandy beach habitats. Her studies have indicated that groomed beaches exhibit the following characteristics, as compared to natural beaches:
- Significantly lower diversity and abundance of wrack-associated animals
- Lower abundance of shorebirds
- Higher relative numbers of flies
- Lower numbers of native plants
- Coarser sand
Here's a Scientific American article that references research by Jenifer Dugan and Dave Hubbard and does a good job of making a case for cute little isopods and against beach grooming.
Given the potential impacts associated with grooming, beach maintenance policies should be given prudent consideration by managers and the public. In many cases, it may be feasible to remove debris through hand raking and other less disruptive methods. And, in places where beach grooming programs are in place, 'wildlife friendly protocols' should be established to ensure that important ecological functions are not disrupted. An example is in San Diego, where beach grooming is only performed above the high tide line during grunion season so as not to disturb or kill grunion eggs deposited in the wet sand.
The subject of beach grooming in California was covered in an article in NOAA's Coastal Services magazine in November/December 2008.
Also see this Making Waves Article from the Beach is Alive series.
The impacts of Beach Maintenance are discussed on the Coastal Care website.